UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Other Discussions > Homebrew Equipment

Notices

Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members.

Reply
 
Thread Tools
Old 28th Feb 2010, 11:09 am   #201
Ed_Dinning
Dekatron
 
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 5,816
Default Re: The "Sussex" Homebrew Valve Tester.

Hi Gents, transformers still available, I'm winding some for the US at present.

Ed
Ed_Dinning is online now   Reply With Quote
Old 28th Feb 2010, 12:34 pm   #202
Andymic
Tetrode
 
Join Date: Jan 2010
Location: Harrow, London, UK.
Posts: 78
Default Re: The "Sussex" Homebrew Valve Tester.

Quote:
Originally Posted by swordholder View Post
Use Rapid 65-1060 50k 10t pot
Mike,

Thanks.

All,

Please note updated BOM. http://spreadsheets.google.com/ccc?k...pfMlE&hl=en_GB
If anyone spots a discrepancy please let me know.

Andy
Andymic is offline   Reply With Quote
Old 1st Mar 2010, 12:40 pm   #203
FRANK.C
Heptode
 
FRANK.C's Avatar
 
Join Date: Feb 2006
Location: Roscommon, Ireland
Posts: 610
Default Re: The "Sussex" Homebrew Valve Tester.

Hi Mike
Sorry if this has been asked before. I had a look through the post and didn't find this question.

In the circuit diagram R3(1M) and R4(10K) are connected in series is this correct?

Thanks in advance
Frank
FRANK.C is offline   Reply With Quote
Old 1st Mar 2010, 1:33 pm   #204
swordholder
Rest in Peace
 
Join Date: Aug 2009
Location: East Preston, Sussex
Posts: 162
Default Re: The "Sussex" Homebrew Valve Tester.

Frank,
Yes this is corect, the 10k is mounted as close as possible to the gate, acting as a stopper.
Possibly an overkill, sort of "belt and braces"
Regards
Mike
swordholder is offline   Reply With Quote
Old 1st Mar 2010, 1:54 pm   #205
FRANK.C
Heptode
 
FRANK.C's Avatar
 
Join Date: Feb 2006
Location: Roscommon, Ireland
Posts: 610
Default Re: The "Sussex" Homebrew Valve Tester.

Hi Mike
Thanks for clarifying that I didn't understand what it was for.
For the sake of a resistor it is better to be safe than sorry.

Frank
FRANK.C is offline   Reply With Quote
Old 1st Mar 2010, 3:10 pm   #206
jakamp58
Diode
 
Join Date: Feb 2010
Location: Groningen, Netherlands.
Posts: 3
Default Re: The "Sussex" Homebrew Valve Tester.

Andy,

Looking over the schematics and BOM, the qty of relays is 3 instead of the noted 2.

Jan
jakamp58 is offline   Reply With Quote
Old 1st Mar 2010, 5:12 pm   #207
real2real
Triode
 
Join Date: Jul 2005
Location: Barnham, Nr Bognor Regis, West Sussex, UK.
Posts: 40
Default Re: The "Sussex" Homebrew Valve Tester.

Mike
I have a 20 k ten turn, I don't see this as a problem, can you confirm ?, its still well within dissipation etc.
Regards
Andy
real2real is offline   Reply With Quote
Old 1st Mar 2010, 5:38 pm   #208
swordholder
Rest in Peace
 
Join Date: Aug 2009
Location: East Preston, Sussex
Posts: 162
Default Re: The "Sussex" Homebrew Valve Tester.

Andy,
I used a 30k just because I had one, I normally say get a 50k, but yours should work OK, although I haven't tried it
Mike
swordholder is offline   Reply With Quote
Old 2nd Mar 2010, 11:02 pm   #209
Andymic
Tetrode
 
Join Date: Jan 2010
Location: Harrow, London, UK.
Posts: 78
Default Re: The "Sussex" Homebrew Valve Tester.

Quote:
Originally Posted by jakamp58 View Post
Looking over the schematics and BOM, the qty of relays is 3 instead of the noted 2.
yes indeed. I had RL1,2 & 3 but hadn't changed the qty.

Thanks
Andymic is offline   Reply With Quote
Old 6th Mar 2010, 1:08 am   #210
Andymic
Tetrode
 
Join Date: Jan 2010
Location: Harrow, London, UK.
Posts: 78
Default Re: The "Sussex" Homebrew Valve Tester.

This has gone quiet.

Is everybody building........................?
Andymic is offline   Reply With Quote
Old 6th Mar 2010, 1:37 am   #211
Guitarist28
Heptode
 
Guitarist28's Avatar
 
Join Date: Dec 2009
Location: Hockley, Essex, UK.
Posts: 559
Default Re: The "Sussex" Homebrew Valve Tester.

...yes, albeit very slowly!

Rob
Guitarist28 is offline   Reply With Quote
Old 6th Mar 2010, 8:26 pm   #212
Pamphonica
Octode
 
Pamphonica's Avatar
 
Join Date: Mar 2008
Location: Virginia Water, Surrey, UK.
Posts: 1,725
Default Re: The "Sussex" Homebrew Valve Tester.

I may have missed this point earlier, as the thread is quite a long one now. I am looking at my own transformer stock to see if I have something suitable.

What is the maximum anode current that can be accurately measured for a given transformer. By my calcs, if the transformer actually produces 250V RMS at 120mA load (as per Ed's version) you could potentially produce (after rectification) about 350V at about 85mA . Does this mean that some output valves like EL34 or KT88/6550 may be pretty near max capability given screen current as well.
Given this should I be looking for a 250V 150-200mA winding to give some headroom?
Any enlightenment welcome.
Many thanks
__________________
Jeremy, G8MLK, BVWTVM Friend, VMARS, BVWS Secretary.
www.pamphonic.co.uk
RetrotechUK (NVCF) May 3rd.
Pamphonica is online now   Reply With Quote
Old 7th Mar 2010, 1:23 pm   #213
swordholder
Rest in Peace
 
Join Date: Aug 2009
Location: East Preston, Sussex
Posts: 162
Default Re: The "Sussex" Homebrew Valve Tester.

Jeremy,
I have used a prototype of Ed transformer with no problems, as I don't tend to leave valves on extended soak test.
Possibly your approach may be better if extended soak testing is envisaged, perhaps Ed may like to comment, as transformer theory is not my forte.
Mike
swordholder is offline   Reply With Quote
Old 7th Mar 2010, 9:09 pm   #214
Ed_Dinning
Dekatron
 
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 5,816
Default Re: The "Sussex" Homebrew Valve Tester.

Hi Mike, Jeremy, the transformer is rated at 100mA on the HT winding for continuous operation and is designed to give the correct output at this level of current, while not overheating.
Short sessions (10-15 secs) at currents up to 300mA , repeated at say 10 min intervals should not be a problem for the transformer.
However, if this is done near max voltage from the regulator, the additional resistive losses in the transformer may cause the anode and screen voltages to reduce on load due to regulation within the transformer.

Hope this helps, Ed
Ed_Dinning is online now   Reply With Quote
Old 7th Mar 2010, 11:19 pm   #215
Pamphonica
Octode
 
Pamphonica's Avatar
 
Join Date: Mar 2008
Location: Virginia Water, Surrey, UK.
Posts: 1,725
Default Re: The "Sussex" Homebrew Valve Tester.

Thanks Ed, that clears things up. I am sure the spec is fine for all normal uses. As I suspected, there may be an impact on the highest HTs but not at lower HT settings.

All I was trying to get straight is the RMS vs rectified DC currents. If the winding gives 100mA at 250V RMS and it is rectified, the DC current limit from the smoothing cap is derated to about 70mA. But at all normal settings (eg 250V DC), there will be ample headroom in the regulator section if slight excess current is drawn for short periods.

Thanks
__________________
Jeremy, G8MLK, BVWTVM Friend, VMARS, BVWS Secretary.
www.pamphonic.co.uk
RetrotechUK (NVCF) May 3rd.
Pamphonica is online now   Reply With Quote
Old 12th Mar 2010, 12:47 pm   #216
real2real
Triode
 
Join Date: Jul 2005
Location: Barnham, Nr Bognor Regis, West Sussex, UK.
Posts: 40
Default Re: The "Sussex" Homebrew Valve Tester.

Quote:
Originally Posted by Andymic View Post
Is everybody building........................?
Andy

Yes, got my transformer from Ed yesterday..forgot to order any knobs!
Andy
real2real is offline   Reply With Quote
Old 12th Mar 2010, 6:07 pm   #217
Alpha_PA
Diode
 
Join Date: Mar 2010
Location: Portsmouth
Posts: 3
Default Re: The "Sussex" Homebrew Valve Tester.

I have just joined this forum and love the look of this project.
Could Martin and Ed please email me their details for purchase of PCB and Tx.

Many Thanks
Alan

E-mail address removed. Please use Private Message system for communication.

Last edited by Brian R Pateman; 12th Mar 2010 at 7:31 pm. Reason: E-mail address removed, previous post reference deleted.
Alpha_PA is offline   Reply With Quote
Old 13th Mar 2010, 2:36 am   #218
Andymic
Tetrode
 
Join Date: Jan 2010
Location: Harrow, London, UK.
Posts: 78
Default Re: The "Sussex" Homebrew Valve Tester.

Chaps,

I've made a couple of changes to the BOM.
The connector for an external heater supply would have been grounded to the chassis and was only rated at 1A 24V. I couldn't find a decent alternative so I've substituted with a pair of 4mm sockets.
If anyone has a better idea I would appreciate it.

Andy
Andymic is offline   Reply With Quote
Old 13th Mar 2010, 11:50 am   #219
Stockden
Hexode
 
Join Date: Mar 2008
Location: Forest of Dean, Gloucestershire, UK.
Posts: 469
Default Re: The "Sussex" Homebrew Valve Tester.

Quote:
Originally Posted by Andymic View Post
Is everybody building........................?
My meters arrived from China yesterday (having taken 3 weeks) so I'm just about ready to start construction.

Hugh
Stockden is offline   Reply With Quote
Old 13th Mar 2010, 10:23 pm   #220
Andymic
Tetrode
 
Join Date: Jan 2010
Location: Harrow, London, UK.
Posts: 78
Default Re: The "Sussex" Homebrew Valve Tester.

I have been designing my panels using Front Panel designer.

See attached
Attached Thumbnails
Click image for larger version

Name:	frontdesignvt1front-001.jpg
Views:	557
Size:	25.4 KB
ID:	33679   Click image for larger version

Name:	frontdesignvt1top-001.jpg
Views:	526
Size:	29.4 KB
ID:	33680  

Last edited by Brian R Pateman; 23rd Mar 2010 at 10:17 pm. Reason: Large embedded images thumbnailed.
Andymic is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 10:41 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Copyright ©2002 - 2020, Paul Stenning.